The present invention relates to a film sensitivity setting device for use in a photographic camera.
More particularly, the present invention concerns a device for enabling an automatic exposure control device of the camera to be adjusted so that exposure is carried out during a condition deviated from a proper one, i.e. over- or under-exposure is intentionally caused.
During actual photographing, there occasionally arises a need wherein it is desired to cause over- or under-exposure with respect to a proper exposure which is effected by an automatic exposure control device. In such cases, the setting of the film sensitivity may be readjusted to cause the desired over- or under-exposure. This adjustment for the intentional deviation of the exposure condition should be carried out with the set film sensitivity value being preserved in some form. For this purpose, one known device includes two knobs of concentrically overlaying construction, with one of the two being a film sensitivity setting knob and the other being a knob for intentional over- or under-exposure. If a film sensitivity is to be set, the two knobs are integrally rotated. When over- or under-exposure is desired, the knob provided for this purpose, i.e., the deviation knob, is depressed or pulled upwardly, so as to be disengaged from the film sensitivity setting knob, thereby enabling the deviation knob to be rotated relative to the film-sensitivity setting knob. While such a construction may appear to be convenient for operation, in practice, it is extremely difficult for the operator to turn the knob, due to the need for depressing or pulling the knob upwardly. In such a device, the film sensitivity setting knob has no locking mechanism, which often results in an erroneous operation, i.e., the film-sensitivity setting knob tends to inadvertently follow the rotation of the exposure deviation setting knob.